Blasting systems



1963 R. v. WAKEFIELD ETAL 3,109,371

BLASTING SYSTEMS Filed Jan. 25, 1960 INVENTOR. RALPH VINCENT WAKEFIELDBHARRY CLARK FOSTER BY %::%W

United States Patent 351699571 BLASEENG SYSTEM-iii Ralph VincentWakefield, Godfrey, and Harry Clark Joster, East Alton, Ill, assignorsto @lin Mat-hieson Qhemieal Corporation, East Alton, ill, a corporationct Virginia Filed la 25, well, Ser. No. 49,348 2 Claims. Cl. mil-25)This invention relates to blasting systems and apparatus andparticularly to such systems utilizing charges of compressed gas as thework performing medium.

A wide variety of compressed gas blasting cartridge-s have beenemployed, particularly in the mining industry to replace explosivecharges. Generally, each cartridge is connected by a high pressure lineto an air compressor or other source of compressed air and thecartridges fired individually when a predetermined discharge pressure isachieved within the cartridge. More recently, a system has been proposedfor connecting a number of such compressed .gas blasting cartridges toone supply source and discharging the cartridges consecutively. Such asystem represents a definite advance over the conventional manner of airshooting but possesses a number of inherent disadvantages. In accordancewith such prior art systems, the control of the flow of high pressuregas is completely dependent upon means in the vicinity of the compressedgas source. Such means normally take the form of a manually controlledvalve and vent in the immediate area of the compressor. Thus, the longextent of high pressure fluid lines between the manual valve and thecompressed gas cartridges is not susceptible to any control. Suchpractice can be quite expensive and, in fact, hazardous. When a break inthe line occurs beyond the manual valve and in the general area of theblasting cartridges, the pressure throughout the entire line is lost.Rebuilding the pressure in the line is quite time consuming and resultsin unnecessary and costly interruptions in the Work day. Also, innumerous cases in which the manually controlled valve fails to operateproperly, the compressed gas will continue to flow to the blastingcartridges. When automatic shells are employed, this results in therepeated charging and discharging of the shells with the attendanthazards both to workmen and the equipment.

it is, therefore, an object of this invention to provide a novel andimproved system and apparatus for the series shooting of compressed gasblasting cartridges overcoming the disadvantages of the prior art.Another object is to reduce operating cost and conservation ofcompressed gas, and to insure more reliable operation of compressed gasblasting cartridges as employed in series shooting. A further object isto provide a compressed gas blasting system in which the possibility ofrepetitive shooting is eliminated. A more specific object is to providea safe, novel, economical method and apparatus for series shooting inwhich the cartridges are charged simultaneously.

The manner in which these and other objects are accomplished will beapparent from the following specification together with the drawing, inwhich:

FIGURE 1 is a schematic representation of a system illustrating thepresent invention; and

FIGURE 2 is a longitudinal sectional view of a valve illustratinganother aspect of the invention.

As shown in FIGURE 1 of the drawing, work face 1 in ice chamber 2 of acoal mine is provided with bore holes 3, 4, and 5, containing automaticcompressed gas blasting cartridges 6, 7 and h respectively. Compressedgas is delivered to the cartridges through main line 9 from a compressoror other suitable source (not shown). The main line is provided with amanually operated control valve It} and means ill for bleeding the line.Main line 9 terminates in manifold 12, and feed lines 13, 14 and 15extend from the manifold to the cartridges in the system. in thispreferred embodiment, cartridges 6, '7 and 8 are completely automaticand will discharge when the pressure therein reaches a predeterminedlevel. Although any type of slu -type, semi-automatic or automatic shellcan be employed, it has been found that an automatic shell of the typedescribed and claimed in the copending application, Serial No. 842,082,of Harry Clark Foster, which is now abandoned, is particularly wellsuited for use in blasting systems and methods of the present type. Theassembly is so designed that the shells will fire sequentially ratherthan simultaneously. This can be accomplished by adjusting each shell todischarge at a different pressure. Alternately, the shells can beadjusted to the same discharge pressure and the pressure diiierentialcan be obtained by varying the length of the feeder line, orifice size,or by any other equivalent means. Thus, all the cartridges in the systemcan discharrge at the same pressure, but the pressure within each shellis obtained after a time lag by restricting or varying the flow of gasinto each shell.

As the compressed gas passes through the manifold,

it is divided into a number of substantially equal portions which arefed to the various cartridges in the system. Thus, prior to thedischarge of any of the cartridges, the pressure throughout the entiresystem is substantially equal and the shells are filled simultaneously.In the present embodiment, cartridge 6 is adjusted to a dischargepressure of approximately 8,000 pounds, cartridge 7 to a dischargepressure of about 8,300 pounds, and cartidge 8 to a discharge pressurein the neighborhod of 8,600 pounds. As illustrated in FIGURE 1, feedline 13 is provided with valve 16 and feed line 14 is provided withvalve 17.

In operation, compressed air or other suitable gas, is supplied tocartridges 6, 7 and 8 through main line 9 and feed lines 13, 1d and 15.The pressure in each of the cartridges increases at a substantiallyequal rate until the discharge pressure, namely 8,0 00 pounds, forcartridge 6 is attained. At this point, the compressed gas contained incartridge 6 is discharged and the coal surrounding the cartridge isbroken down. Immediately upon discharge of cartridge 6, cut-oil valve l6stops the fiow of air through feed line 13. The air flow from main line9 is then equally divided between teed lines 14 and 15. This conditioncontinues until the pressure in the system reaches about 8,300 pounds,at which level cartridge 7 is discharged. Cu -o1i valve 17 thenimmediately closes feed line 34 and all of the air from the main line isthen directed through feed line 15 into cartridge 8, which subsequentlydischarges at a pressure of about 8,606 pounds. It will be noted thatfeed line 15 in this embodiment is not provided with a cut-oil valve asshown in the remaining tfeed lines. Normally, it is not necessary toprovide the feed line for the last firing cartridge with such a cut-offmeans. However, if desired, each of the feed lines can be provided =49with a cut-off means to insure positive protection against loss ofpressure throughout the system upon a failure of any part thereof. Aftercartridge 8 has been discharged, valve 16 is closed to stop theintroduction of air into the system. The residual pressure in the linescan then be relieved through means 21.

Valves l6 and 17 can be of any appropriate design. It is necessary thatthey stop the flow of compressed gas through the feed line when thecorresponding cartridge has been discharged, and reset automatically topermit charging for succeeding shots. in addition, such valves must notclose prematurely as during charging.

A valve means particularly well suited for employment in accordance withthe assembly of the present invention is illustrated in FIGURE 2. Thisvalve assembly is provided with an inlet body 18 and an outlet cap 19which are screw threadedly connected as indicated at 2G. The sealbetween the inlet body and the outlet cap is completed by resilientsealing means 21 positioned in groove 22 of the inlet body. Asubstantially cylindrical chamber 23 is contained within the inlet bodyand accommodates valve piston 24. A sliding seal between the wall ofchamber 23 and valve piston 24 is provided by O-ring 25 positioned ingroove 26 of the valve piston 24. Suitable means for connecting thevalve body to the feeder line or between the feeder line and thecartridge are provided on the inlet body at 2'7 and on the outlet cap at28. Also, the outlet cap is provided with opposed notched portions 29 orother suitable means to accommodate a wrench. Stem 39- of valve piston24 forms a sliding fit with the inlet body at 31 so as to provide arelatively small annular passageway into obturated chamber 32. Theassembly is so designed that the inlet port 33, bore 34 in the valvepiston, and the outlet port 35 are in substantial alignment. The outletport is spanned by valve seat 36 which is provided with diagonal ports37 and central depression 38 in the face thereof. Central depression 38must be larger in diameter than the outside diameter of stem 30 of thevalve piston. The design of the valve can be modified by making thevalve face planar and positioning a central depression in the base ofthe valve piston or in some instances, both the valve piston and thevalve face can be dished to provide a larger air space between them.Likewise, annular space 39 can be formed by either member.

At the start of normal operation, valve piston 24 is in the positionshown in FIGURE 2. The compressed gas enters inlet body 18 through inletport 33, passes through bore 34 of valve piston 24, between the valvepiston 24 and valve seat 36, and then through annular space 39. The airthen continues through diagonal ports 37 in the valve seat and throughthe outlet port 35 to the cartridge being charged. Valve piston 24- Willremain in the position shown during the charging of the cartridge. Evenif the valve piston is in contact with the valve seat when compressedgas is first introduced into the valve, the valve piston willnecessarily assume the position as shown in the drawing. This will beapparent from the following explanation.

Air can enter obturated chamber 32. only through a very small clearanceat sliding fit '31 around stem 30 of the valve piston. Thus, it passesthrough bore 34 and out let port 35 at a much greater rate than itenters obturated chamber 32 through sliding fit 31. Therefore, the firstincrement of air being charged is momentarily effective on that portionof the valve piston 34 which is opposite central depression 38 and onthe external diameter of stem 30 of the valve piston. Since the diameterof depression 33 is slightly larger than the external diameter of stem39, the differential effective areas of valve piston 24 when in contactwith valve seat 35 will initiate movement of the valve piston to theleft and away from the valve seat. This slight movement of the valvepiston toward the left exposes the full area of the valve face at theright end of piston 24 to the air pressure. Although the chargingpressure may drop somewhat as the air is permitted to flow throughoutlet port 35 into the shell, the relatively lower pressure in chamber32 at this point permits the piston 24 to complete its shift to theleft. During further charging of the shell with an increase of pressure,both in the line and in the valve, the pressure in obturated chamber 32gradually increases and becomes substantially equal to the pressurethroughout the remainder of the system. This increase in pressure inchamber 32 will have no immediate effect on the position of the pistonsince the pressures and areas 'on the right and loft ends of the pistonare in substantial balance.

When the cartridge attached to outlet cap 19 discharges, the pressure onthe right end face of valve piston 24 is substantially reduced. Due tothe large bore in the piston, it is quite likely that there may also bea lowering of pressure on the left end of piston stem 30. However, thepressure in chamber 32 will decrease at a much slower rate. Thus, thehigh pressure air trapped in chamber 32 expands and forces valve piston24 against valve seat 36. The residual back pressure from the cartridgeis then effective only upon the reduced annular area of piston 24 inannular space 39 While the line pressure is effective on the entire leftside of the piston and on the right hand portion of the piston oppositecentral depression '58. Therefore, the effect of these clifierentialareas is to hold the valve piston 24 closed against seat 36 and toprevent further flow of compressed gas into the discharged shell whilecharging of the other shells in the system continues. After the lastshell in the system has been fired, control valve is is manually closedand the pressure in the line reduced by bleeding at 11. As the linepressure falls sufficiently below the residual pressure in each shell,the valve pistons are urged to the left. This permits bleeding ofresidual pressure from the cartridges and concomitantly resets the valvefor the next charging cycle.

Valves of the type shown or any cut-oil valve with equal capabilitiescan be utilized to advantage in accordance with the present inventionfor the firing of a plurality of compressed gas blasting cartridges froma common supply line. Valve piston 24 can be replaced by a cup shapedvalve member slidable within bore 23 while utilizing the principles ofthe valve shown. In addition, it will be appreciated that valves of thistype can be used in single firing operations to prevent air from leakinginto the shell after discharge. Thus, the possibility of the cartridgedischarging repeatedly is reduced to an absolute minimum. The presentinvention also positively insures that the air supply is shut offimmediately upon discharge of the shell. This not only conserves airwhen slug type shells are employed but also facilitates the utilizationof completely automatic shells by eliminating double shooting.

In the assembly described herein, each of the feed lines, with theexception of the one connected to the last discharging cartridge isprovided with a cut-off valve. While such a valve is not necessary tothe last feed line, it can be used to advantage and will prevent loss ofpressure in the system, should a break occur beyond the valve. Also,cut-off valves of the type described can be placed at intervals in themain line for the same purpose.

The connection between the main line and the feed lines is mostconveniently made through a manifold as indicated in FIGURE 1 of thedrawing. Any type of manifold adaptable to high pressure usage can beemployed. Alternately, the connection between the main line and feedline can be through a series of junctures or in any other conventionalmanner.

Although the invention has been described in considerable detail in theforegoing for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that many modifications canbe made without departing from the spirit and scope of the invention.

What is claimed is:

l. A system for discharging a plurality of compressed gas blastingcartridges in a predetermined order comprising a main high pressurefluid line extending from a source of compressed gas to a pointproximate the work face to be broken down, amanually controlled valve inthe main line, a plurality of blasting cartridges positioned in the workface and being provided with mechanisms to release a charge ofcompressed gas at predetermined discharge pressures, each of saidcartridges having a dilferent discharge pressure, a manifold connectedto said main line proximate the work face, a feed line extending fromeach cartridge and connected to the main line through said manifold, apressure actuated cut-off valve in each feed line except one, eachcut-off valve being positioned between the release mechanism of acartridge and said manifold, means in each pressure responsive cutoffvalve being adapted to allow the simultaneous charging of the cylindersand to stop the flow of air through lines after the cartridges have beendischarged.

References Cited in the file of this patent UNITED STATES PATENTS2,146,879 Armstrong Feb. 14, 1939 2,403,689 Sprague July 9, 19462,633,147 Badami Mar. 31, 1953 2,710,626 Burdick et al June 14, 19552,858,764 Hesson et al Nov. 4, 1958 2,867,426 Dowie Jan. 6, 19593,041,969 Filstrup July 3, 1962

1. A SYSTEM FOR DISCHARGING A PLURALITY OF COMPRESSED GAS BLASTINGCARTRIDGES IN A PREDETERMINED ORDER COMPRISING A MAIN HIGH PRESSUREFLUID LINE EXTENDING FROM A SOURCE OF COMPRESSED GAS TO A POINTPROXIMATE THE WORK FACE TO BE BROKEN DOWN, A MANUALLY CONTROLLED VALVEIN THE MAIN LINE, A PLURALITY OF BLASTING CARTRIDGES POSITIONED IN THEWORK FACE AND BEING PROVIDED WITH MECHANISMS TO RELEASE A CHARGE OFCOMPRESSED GAS AT PREDETERMINED DISCHARGE PRESSURES, EACH OF SAIDCARTRIDGES HAVING A DIFFERENT DISCHARGE PRESSURE, A MANIFOLD CONNECTEDTO SAID MAIN LINE PROXIMATE THE WORK FACE, A FEED LINE EXTENDING FROMEACH CARTRIDGE AND CONNECTED TO THE MAIN LINE THROUGH SAID MANIFOLD, APRESSURE ACTUATED CUT-OFF VALVE IN EACH FEED LINE EXCEPT ONE, EACHCUT-OFF VALVE BEING POSITIONED BETWEEN THE RELEASE MECHANISM OF ACARTRIDGE AND SAID MANIFOLD, MEANS IN EACH PRESSURE RESPONSIVE CUTOFFVALVE BEING ADAPTED TO ALLOW THE SIMULTANEOUS CHARGING OF THE CYLINDERSAND TO STOP THE FLOW OF AIR THROUGH THE CORRESPONDING FEED LINE WHEN THECARTRIDGE ATTACHED THERETO IS DISCHARGED.